JP3490977B2 - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which is equipped with an ohmic electrode capable of being formed without necessity of alloying by heat treatment and capable of preserving extremely stable properties even under each kind of high-temperature conditions in a manufacturing process or an assembly process. SOLUTION: For a light emitting diode 100, an n-GaN layer 2, a light emitting layer 3, and a p-GaN layer 4 are stacked in order on a sapphire board. A p-electrode 5 is made in close contact on the p-GaN layer 4, making ohmic contact. Moreover, an n-electrode 8 where an AlSi alloy film 6 and a Zn film 7 are stacked in order is made in close contact on the n-GaN layer 2, making ohmic contact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to III-V such as BN (boron nitride), GaN (gallium nitride), AlN (aluminum nitride), InN (indium nitride) or TlN (thallium nitride) or their mixed crystals. The present invention relates to a semiconductor element made of a group nitride-based semiconductor (hereinafter referred to as a nitride-based semiconductor) and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, GaN semiconductor light emitting devices have been put into practical use as semiconductor light emitting devices such as light emitting diodes emitting blue or violet light, semiconductor laser devices and the like. A transistor using a GaN-based semiconductor has also been proposed. In such a GaN-based semiconductor element, Ga
An electrode that makes ohmic contact with the N-based semiconductor is required.

FIG. 17 is a schematic process sectional view showing an example of a conventional method for manufacturing a GaN-based semiconductor laser device.

When manufacturing a semiconductor laser device, first, as shown in FIG. 17A, on a sapphire substrate 60, a buffer layer 61, an n-contact layer 62, an n-clad layer 63, a light emitting layer 64, and a p- layer. The clad layer 65 and the p-contact layer 66 are sequentially grown by MOCVD (metal organic chemical vapor deposition) or the like.

Thereafter, as shown in FIG. 17B, p-
A partial region from the contact layer 66 to the n-contact layer 62 is etched by using, for example, a dry etching technique using CF ₄ gas to expose the n-contact layer 62.

Next, as shown in FIG. 17C, a Ni film is formed on a predetermined region of the p-contact layer 66 by, for example, an electron beam evaporation method to form a p-electrode 67. Further, for example, the N of the p-electrode 67 selectively formed in this way is
Using the i film as a mask, a partial region from the p-contact layer 66 to the p-cladding layer 65 is etched by a dry etching technique to expose a predetermined region of the p-cladding layer 65.

Subsequently, as shown in FIG. 17D, a Ti film 68 and an Al film 69 are sequentially laminated on the exposed predetermined region of the n-contact layer 62 by, for example, an electron beam evaporation method to form an n electrode 70. To do.

Further, as shown in FIG. 17 (e), the back surface of the sapphire substrate 60 of the semiconductor laser device manufactured as described above is bonded and fixed to the stem 75 by a die bonding technique using AuSn alloy solder or the like. . In such a die-bonding process, heating at about 300 to 400 ° C. is required for melting solder or the like. next,
In this way, the p electrode 67 and the n electrode 70 of the semiconductor laser device fixed on the stem 75 are connected to an external circuit by a wire bonding technique using a wire 81 made of Au or the like. Thereby, a semiconductor light emitting device is formed.

[0009]

As described above, in the conventional semiconductor laser device, the Ti film 68 and the Al film 69 are used.
An n-electrode 70 having a structure in which and are sequentially stacked is generally used. Such an n-electrode 70 has ohmic characteristics when formed as shown in FIG. 17D, but is deteriorated by heating in a post-treatment step, for example, heating at about 300 to 400 ° C. in a die bonding step shown in FIG. 17E. And becomes a non-ohmic electrode.

The Ti film 68 and the Al film 69 as described above
When the change in the current-voltage characteristic when the n-electrode 70 formed by sequentially stacking is heat-treated is examined, the following results are obtained.

When measuring the current-voltage characteristics of the n-electrode 70, a pair of n-electrodes 70 made of a Ti film 68 and an Al film 69 are formed on the n-GaN layer 90 as shown in FIG. The voltage applied between the pair of n electrodes 70 and the current flowing between the n electrodes 70 are measured. here,
In this case, the carrier concentration of the n-GaN layer 90 is 4 × 10.
¹⁸ cm ⁻³ . Here, a Ti film 68 with a film thickness of 5 nm and an Al film 69 with a film thickness of 300 nm are formed by the electron beam evaporation method.
To form.

When the current-voltage characteristics of the n-electrode 70 composed of the Ti film 68 and the Al film 69 are measured by the above method, the results shown in FIG. 19 are obtained. As shown in the graph V of FIG. 19, the n-electrode 70 which has not been subjected to the heat treatment after vapor deposition has a slight rectifying property.

On the other hand, as shown in Graphs W and X, the n-electrode 70 which has been subjected to heat treatment at 200 ° C. and 300 ° C. after vapor deposition has an ohmic characteristic deteriorated by the heat treatment and becomes an electrode having a perfect rectifying property. . Also, graph Y
And as shown in Graph Z, in the n-electrode 70 which was heat-treated at 400 ° C. and 500 ° C. after vapor deposition formation,
The rectifying property is lost as compared with the n-electrode 70 heat-treated at 200 ° C. or 300 ° C.
Even in the n-electrode 70 that has been heat-treated at 0 ° C., the ohmic characteristics continue to deteriorate.

As is apparent from the above measurement of the current-voltage characteristics, the n-electrode 7 composed of the Ti film 68 and the Al film 69.
At 0, heating in the temperature range of 200 to 500 ° C. deteriorates the ohmic characteristics of the electrode. Here, such a heating temperature range corresponds to the heating temperature in the post-treatment process of the device, for example, the heating temperature in the die bonding process at the time of assembling the device as described above. Therefore, Ti
Degradation of the ohmic characteristics of the n-electrode 70 formed of the film 68 and the Al film 69 by heating at 200 to 500 ° C. is a very important problem in manufacturing the device.

By the way, as a method for realizing the stable ohmic electrode by preventing the deterioration of the ohmic characteristics of the n-electrode 70 as described above, after the Ti film 68 and the Al film 69 are laminated to form the n-electrode 70, This n electrode 7
There is a method of heat-treating 0 at 500 to 600 ° C. For example, n formed by stacking a Ti film 68 and an Al film 69
The electrode 70 is heat-treated at 650 ° C. for about 5 minutes in an atmosphere such as nitrogen to alloy it. Thereby, it becomes possible to realize a stable ohmic electrode in the n-electrode 70.

However, p as shown in FIG.
In the method of manufacturing the element in which the n-electrode 70 is formed after the electrode 67 is formed, the ohmic characteristics of the p-electrode are deteriorated by heat in the heat treatment process of the n-electrode 70 at 500 to 600 ° C. as described above. Therefore, it is difficult to carry out such heat treatment of the n-electrode 70. As described above, in the method of preventing the ohmic characteristics of the n-electrode 70 from being deteriorated by performing the heat treatment, there are restrictions in the manufacturing process of the element, and therefore, it is necessary to consider the timing at which the heat treatment can be performed.

The object of the present invention is an ohmic material which can be formed without alloying by heat treatment and can maintain extremely stable characteristics under various high temperature conditions during the manufacturing process and the assembly process. An object of the present invention is to provide a semiconductor device including an electrode.

Another object of the present invention is that it can be formed without alloying by heat treatment, and can maintain extremely stable characteristics even under various high temperature conditions during the manufacturing process and assembly process. Another object of the present invention is to provide a method for manufacturing a semiconductor device having a different ohmic electrode.

[0019]

A semiconductor device according to the present invention is a semiconductor device provided with an n-type nitride semiconductor and an ohmic electrode formed on the n-type nitride semiconductor. And the ohmic electrode includes a first metal film containing zinc , and the first metal film is densely formed on the second metal film.
It is formed by wearing .

The semiconductor device according to the present invention comprises an ohmic electrode having a first metal film containing zinc. Such an ohmic electrode is extremely stable under high temperature conditions and can maintain good ohmic characteristics without alloying by heat treatment.

Therefore, in the semiconductor device according to the present invention, the characteristics of the ohmic electrode do not deteriorate even under high temperature conditions during the manufacturing process and the assembly process of the semiconductor device, and the ohmic resistance is extremely stable and highly reliable. It becomes possible to realize electrodes.

[0022]

Normally, even if an attempt is made to form an ohmic electrode by directly forming a first metal film containing zinc on the n-type nitride-based semiconductor layer by a lift-off method, this method does not work on the n-type nitride-based semiconductor layer. Since the first metal film cannot be formed, the ohmic electrode cannot be formed in this case.

On the other hand, when the second metal film containing the aluminum-silicon alloy is formed and the first metal film made of zinc is formed on the second metal film as described above to form the ohmic electrode, Since the first metal film is formed on the n-type nitride semiconductor layer via the second metal film, the ohmic electrode can be easily formed by the lift-off method.

The ohmic electrode may further include a third metal film containing gold and formed in close contact with the first metal film. In the ohmic electrode in which the third metal film made of gold is formed on the first metal film made of zinc as described above, zinc is not covered by gold, that is, the first ohmic electrode is formed. Compared to the case where the third metal film is not formed on the metal film of (3), it is extremely stable under higher temperature conditions, and it becomes possible to maintain good ohmic characteristics.

Further, in this case, since the surface of the ohmic electrode is constituted by the third metal film made of gold, it is possible to perform wire bonding by using this third metal film as a bonding pad. At the same time, the adhesion strength with the gold wire can be improved.

The ohmic electrode is formed in close contact with the first metal film and is formed of a third or third metal film containing nickel, platinum, palladium, molybdenum, gold, tantalum, tungsten or gold-zinc alloy. A metal film and a fourth metal film, which is formed on the third metal film so as to be in close contact with each other and contains gold, may be further provided.

In the ohmic electrode in which the third and fourth metal films made of the above metal are formed on the first metal film made of zinc as described above, since zinc is coated, If not covered, ie first
Compared to the case where the third and fourth metal films are not formed on the metal film of (1), it is extremely stable under higher temperature conditions and can maintain good ohmic characteristics.

Further, in this case, since the surface of the ohmic electrode is constituted by the fourth metal film made of gold, wire bonding can be performed by using this fourth metal film as a bonding pad. At the same time, the adhesion strength with the gold wire can be improved.

The n-type nitride semiconductor may contain at least one of boron, gallium, aluminum, indium and thallium.

The thickness of the second metal film is preferably 70 nm or less. In the ohmic electrode in which the thickness of the second metal film made of an aluminum-silicon alloy is larger than 70 nm, the ohmic characteristics deteriorate under high temperature conditions. On the other hand, the thickness of the second metal film is 70
In the ohmic electrode having a thickness of nm or less, the ohmic characteristics do not deteriorate even under high temperature conditions.
It is extremely stable and can maintain good ohmic characteristics.

A method of manufacturing a semiconductor device according to the present invention is
comprising forming an n-type nitride-based semiconductor, and forming an ohmic electrode without performing heat treatment by forming a first metal film including a zinc n-type nitride semiconductor, an ohmic electrode Forming the n-type nitride
The second one consisting of aluminum-silicon alloy on the base semiconductor
A step of forming a metal film in close contact, and a step of forming a metal film on the second metal film.
And a step of forming a metal film of No. 1 in close contact with each other .

In the method of manufacturing a semiconductor device according to the present invention, the ohmic electrode having the first metal film containing zinc is formed on the n-type nitride semiconductor layer. The ohmic electrode formed in this manner is extremely stable under high temperature conditions and can maintain good ohmic characteristics without alloying by heat treatment. Therefore, in the method for manufacturing a semiconductor device according to the present invention, the ohmic electrode does not deteriorate in characteristics even under high temperature conditions during the manufacturing process and the assembling process of the semiconductor device.

As described above, according to the method of manufacturing a semiconductor device of the present invention, it is possible to manufacture a semiconductor device having an ohmic electrode which is extremely stable and highly reliable.

[0035]

Usually, even if an attempt is made to form an ohmic electrode by directly forming a first metal film containing zinc on the n-type nitride semiconductor layer by a lift-off method, this method will form an ohmic electrode on the n-type nitride semiconductor layer. Since the first metal film cannot be formed, the ohmic electrode cannot be formed in this case.

On the other hand, in the method of forming the second metal film containing the aluminum-silicon alloy and then forming the first metal film made of zinc on the second metal film to form the ohmic electrode, as described above, Since the first metal film is formed on the nitride-based semiconductor layer via the second metal film, the ohmic electrode can be easily formed by the lift-off method.

The step of forming the ohmic electrode may further include the step of forming a third metal film containing gold in close contact with the first metal film. In the method of forming the ohmic electrode by forming the third metal film made of gold on the first metal film made of zinc in this way, since zinc is covered with gold, it is not covered with gold, that is, As compared with the case where the third metal film is not formed on the first metal film, it is possible to realize an ohmic electrode that is extremely stable even under higher temperature conditions and can maintain good ohmic characteristics.

Since the surface of the ohmic electrode formed by the above method is composed of the third metal film made of gold, wire bonding should be performed by using this third metal film as a bonding pad. It becomes possible to improve the adhesion strength with the gold wire.

In the step of forming the ohmic electrode, nickel, platinum, palladium, molybdenum,
A step of closely forming a third metal film made of one or more metal films containing gold, tantalum, tungsten or a gold-zinc alloy, and a fourth metal film containing gold on the third metal film. It may further include a step of forming the layers in close contact with each other.

In the method of forming the ohmic electrode by forming the third and fourth metal films made of the above metal on the first metal film made of zinc as described above, the ohmic electrode is coated with zinc. Therefore, as compared with the case where zinc is not coated, that is, the case where the third and fourth metal films are not formed on the first metal film, extremely stable and good ohmic characteristics are obtained even under higher temperature conditions. An ohmic electrode that can be held can be realized.

Since the surface of the ohmic electrode formed by the above method is formed of the fourth metal film made of gold, wire bonding is performed by using this fourth metal film as a bonding pad. It becomes possible to improve the adhesion strength with the gold wire.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a light emitting diode element will be described as a semiconductor element according to the present invention.

FIG. 1 is a schematic sectional view showing an example of a light emitting diode element according to the present invention. The light emitting diode element 100 shown in FIG. 1 is manufactured by the manufacturing method shown in FIGS.

When manufacturing the light emitting diode element 100, as shown in FIG. 2A, first, the n-GaN layer 2, the light emitting layer 3 and the p-GaN layer 4 are formed on the sapphire substrate 1 by the MOCVD method ( Metal organic chemical vapor deposition method) and the like are sequentially grown. Then, from the p-GaN layer 4 to the n-G
A partial region up to the aN layer 2 is etched by a method such as dry etching to expose the n-GaN layer 2.

Next, as shown in FIG. 2B, p-Ga
A photoresist pattern 50 is formed on the exposed upper surfaces of the N layer 4 and the n-GaN layer 2. The photoresist pattern 50 has an opening 51 on the p-GaN layer 4. In this state, a 300 nm-thick Ni film 5a is formed on the p-GaN layer 4 in the opening 51 and on the photoresist pattern 50 by an electron beam evaporation method.

After that, as shown in FIG. 2C, the Ni film 5a on the photoresist pattern 50 is removed together with the photoresist pattern 50 by the lift-off method. In this way, the p-electrode 5 made of the Ni film is formed.

Then, as shown in FIG. 3D, p-G
A photoresist pattern 52 is formed on the aN layer 4, the p electrode 5, and the exposed upper surface of the n-GaN layer 2. The photoresist pattern 52 has an opening 53 on the exposed upper surface of the n-GaN layer 2. In this state, the opening 53
An AlSi alloy film 6a having a film thickness of 15 nm is formed on the upper surface of the n-GaN layer 2 and the photoresist pattern 52 by an electron beam evaporation method, and the AlS
A Zn film 7a having a thickness of 100 nm is formed on the i alloy film 6a by an electron beam evaporation method. In this case, AlS
The Si content in the i alloy film 6a is 1% by weight.

After the above, the AlSi alloy film 6a and the Zn film 7a on the photoresist pattern 52 are removed together with the photoresist pattern 52 by the lift-off method.
Thereby, the n-electrode 8 (FIG. 1) is formed by sequentially stacking the AlSi alloy film 6 and the Zn film 7.

The light emitting diode device 100 of FIG. 1 is manufactured by the above method. This light emitting diode element 10
At 0, the p-electrode 5 is in ohmic contact with the p-GaN layer 4 and the n-electrode 8 is in ohmic contact with the n-GaN layer 2.

In the light emitting diode device 100, n
Since the electrode 8 is composed of the Zn film 7, the ohmic characteristics of the n-electrode 8 do not deteriorate even if heating is performed in the temperature range up to about 400 ° C. Therefore, in the manufacturing process, the assembly process, etc.
Even if the n-electrode 8 is heated in a temperature range of not higher than 00 ° C., the ohmic characteristics of the n-electrode 8 do not deteriorate, and it is possible to realize the stable and highly reliable n-electrode 8 which makes ohmic contact with the n-GaN layer 2. It will be possible.

As described above, in the light emitting diode device 100, since the n electrode 8 is composed of the Zn film 7, it is an ohmic electrode having an extremely stable characteristic easily without alloying by heat treatment. It is possible to obtain the electrode 8.

By the way, in the light emitting diode element 100, Z is formed on the n-GaN layer 2 via the AlSi alloy film 6.
The n film 7 is formed and the n electrode 8 is formed, for the following reason.

For example, in the step of forming the n electrode 8 shown in FIG. 3D, the AlSi alloy film 6a is formed on the n-GaN layer 2.
If not formed, Zn is formed on the photoresist pattern 52.
Although the film 7a can be formed by vapor deposition, the n-GaN layer 2
The Zn film 7a cannot be vapor-deposited on it. Although the n-electrode 8 is formed using the photoresist pattern 52 here, the photoresist pattern 52 is also used when the n-electrode 8 is formed using a Si oxide film instead of the photoresist pattern 52. As in the case, if the AlSi alloy film 6a is not formed, n-GaN is formed.
The Zn film 7a cannot be formed on the layer 2 by vapor deposition.

As described above, when the AlSi alloy film 6a is not formed, the semiconductor surface, that is, the surface of the n-GaN layer 2 is formed by the method of forming the n-electrode 8 by the lift-off technique as shown in FIG. 3D. The Zn film 7a cannot be formed by vapor deposition. Therefore, the Zn film 7 cannot be formed to form the n-electrode 8 without the AlSi alloy film 6 interposed.

On the other hand, instead of the lift-off method described above, A
Zn is directly formed on the n-GaN layer 2 without interposing the 1Si alloy film 6.
As a method of forming the film 7 and using it as an n-electrode,
A method is conceivable in which after forming the entire surface of the GaN layer 2, a predetermined region is etched and removed to form an n-electrode having a predetermined shape.

However, in this case, since Zn has a large ionization tendency and reacts very easily with acid or alkali, the Zn film 7 may be dissolved in the solvent used in the photolithography process or the etching process. Therefore, it is difficult to form the n-electrode made of the Zn film 7 into an electrode shape by such a method.

On the other hand, according to the method of the present invention, A
Since the Zn film 7 is formed on the n-GaN layer 2 via the lSi alloy film 6, the n electrode 8 composed of the Zn film 7 can be easily formed by the lift-off method.

If an Al film is formed instead of the AlSi alloy film 6 and the Zn film 7 is formed on this Al film, Al and Zn react with each other, and Zn having a uniform film thickness is formed.
The film 7 cannot be formed. On the other hand, as described above, Z is formed on the n-GaN layer 2 via the AlSi alloy film 6.
When the n film 7 is formed, the Zn film 7 having a uniform film thickness can be formed.

Next, regarding the n-electrode 8 formed by sequentially laminating the AlSi alloy film 6 and the Zn film 7 as described above, 30
The current-voltage characteristics were examined when the heat treatment was performed at 0 ° C. and when the heat treatment was not performed.

When measuring such current-voltage characteristics, as shown in FIG. 4, an AlSi alloy film 6 and a Zn film 7 are sequentially laminated by an electron beam evaporation method to form an n-
A pair of n electrodes 8 is formed on the GaN layer 10, and the pair of n electrodes 8 is formed.
The voltage applied between the electrodes 8 and the current flowing between the pair of n electrodes 8 were measured. Here, the carrier concentration of the n-GaN layer 10 is set to 4 × 10 ¹⁸ cm ⁻³ , and the AlSi alloy film 6 is formed.
Had a thickness of 30 nm. Further, the thickness of the Zn film 7 is set to 10
The measurement was performed for each of the cases of nm and 100 nm.

FIG. 5 shows the current flowing through the n-electrode 8 formed by sequentially stacking the AlSi alloy film 6 and the Zn film 7 by the above method.
It is a figure which shows the result of having measured the voltage characteristic. In FIG. 5, graph A shows the result of the n-electrode 8 which was not subjected to any heat treatment after vapor deposition, and graph B shows
It shows the result of the n-electrode 8 which was heat-treated at 300 ° C. for 5 minutes in a nitrogen atmosphere after vapor deposition.

As shown in the graph A of FIG. 5, good ohmic characteristics can be obtained in the n-electrode 8 which is not subjected to the heat treatment regardless of whether the film thickness of the Zn film 7 is 10 nm or 100 nm. Further, as shown in Graph B, in the n-electrode 8 composed of the Zn film 7,
Regardless of whether the thickness of the Zn film 7 is 10 nm or 100 nm, even if heat treatment is performed at 300 ° C. for 5 minutes, the ohmic characteristics of the electrodes do not deteriorate and good ohmic characteristics are obtained.

For comparison, an n-electrode composed of only an AlSi alloy film was prepared, and the effect of heat treatment on the current-voltage characteristics of this n-electrode was measured and examined by the same method as above. . In this case, the thickness of the AlSi alloy film forming the n-electrode was 150 nm.

FIG. 6 is a diagram showing the measurement results of the current-voltage characteristics of the n-electrode composed only of the AlSi alloy film.
In FIG. 6, graph C shows the result of the n-electrode which was not subjected to any heat treatment after formation, and graph D
Shows the result of the n-electrode which was heat-treated at 300 ° C. for 5 minutes in a nitrogen atmosphere after formation.

As shown in the graph C of FIG. 6, in the n-electrode formed only of the AlSi alloy film, as in the case of the n-electrode 8 formed of the AlSi alloy film 6 and the Zn film 7 described above, it is favorable when the heat treatment is not performed. Good ohmic characteristics can be obtained. On the other hand, as shown in the graph D, in the n-electrode composed only of the AlSi alloy film, if the heat treatment is carried out at 300 ° C. for 5 minutes, the ohmic characteristics of the electrode are deteriorated and the electrode has a rectifying property.

From the above, it is clear that by using the Zn film as the constituent material of the n-electrode, an n-electrode which is stable even when the temperature changes and can prevent the deterioration of the ohmic characteristics due to the heat treatment can be obtained. It was

Next, with respect to the n-electrode 8 composed of the AlSi alloy film 6 and the Zn film 7, the optimum film thickness of the AlSi alloy film 6 was examined. The result is shown in FIG. 7.

In this case, the film thickness of the Zn film 7 is constant at 15 nm, and the film thicknesses of the AlSi alloy film 6 are 10 nm, 30 nm, 70 nm and 80 nm, respectively. The current-voltage characteristics were measured.

In FIG. 7, graph E shows that the film thickness of the AlSi alloy film 6 which was not subjected to any heat treatment after formation was 10
nm, 30 nm, 70 nm, and 80 nm n-electrodes 8
It shows the result of. On the other hand, graphs F to I show the case where the heat treatment was performed at 300 ° C. for 5 minutes in a nitrogen atmosphere after the formation, and the graph F shows the results of the n-electrode 8 in which the thickness of the AlSi alloy film 6 was 10 nm. G is Al
The results of the n-electrode 8 having the Si alloy film 6 having a film thickness of 30 nm are shown. Graph H shows the n-electrode having the AlSi alloy film 6 having a film thickness of 70 nm.
The result of the electrode 8 is shown, and the graph I shows the result of the n-electrode 8 in which the thickness of the AlSi alloy film 6 is 80 nm.

As shown in the graph E of FIG. 7, the thickness of the AlSi alloy film 6 is 10 nm, 30 nm, 70 nm and 8 nm.
In any case of 0 nm, good ohmic characteristics are obtained in the n-electrode 8 which is not heat-treated. Further, as shown in Graphs F to H, when the thickness of the AlSi alloy film 6 is 10 nm, 30 nm and 70 nm, the ohmic characteristics of the electrode do not deteriorate even if the heat treatment is performed at 300 ° C. for 5 minutes, which is good. Good ohmic characteristics can be obtained.

On the other hand, as shown in Graph I, A
When the thickness of the 1Si alloy film 6 is 80 nm, 3
When heat treatment is performed at 00 ° C. for 5 minutes, the ohmic characteristics of the electrode deteriorate, and the electrode has a rectifying property.

From the above, in the n-electrode 8 composed of the AlSi alloy film 6 and the Zn film 7, AlSi
It was revealed that by setting the thickness of the alloy film 6 to 70 nm or less, it is possible to realize a stable ohmic electrode without deterioration of characteristics due to heat treatment.

The AlS in the n-electrode 8
The thickness of the i alloy film 6 is more preferably 30 nm or less, and most preferably 20 nm or less. By setting the film thickness of the AlSi alloy film 6 in the n-electrode 8 in such a range, it is possible to obtain good ohmic characteristics even when the heat treatment is performed, as when the heat treatment is not performed.

Next, with respect to the n-electrode 8 composed of the AlSi alloy film 6 and the Zn film 7, the optimum film thickness of the Zn film 7 was examined. The result is shown in FIG. In this case, the AlSi alloy film 6 has a constant film thickness of 15 nm, and the Zn film 7 has a film thickness of 10 nm and 50 n, respectively.
m, 150 nm and 1.0 μm, the current-voltage characteristics were measured by the same method as described above in FIG.

In FIG. 8, a graph J shows that the Zn film 7 which has not been subjected to any heat treatment after formation has a thickness of 10 nm, 5
It shows the results for each n-electrode 8 of 0 nm, 150 nm and 1.0 μm. On the other hand, graph K shows that the Zn film 7 having a thickness of 10 nm, 50 nm, 150 nm, and 1.0 μm, which has been subjected to heat treatment at 300 ° C. for 5 minutes in a nitrogen atmosphere after formation.
The results of the respective n electrodes 8 are shown.

As shown in the graph J of FIG. 8, the thickness of the Zn film 7 is 10 nm, 50 nm, 150 nm and 1.0 μm.
In any case of m, n was not heat treated
Good ohmic characteristics are obtained in the electrode 8.
Further, as shown in the graph K, the film thickness of the Zn film 7 is 10 n.
In the case of m, 50 nm, 150 nm, and 1.0 μm, such n-electrode 8 has 300
Even if the heat treatment is performed at 5 ° C. for 5 minutes, the ohmic characteristics of the electrode do not deteriorate and good ohmic characteristics can be obtained.

Thus, the AlSi alloy film 6 and the Zn
In the n-electrode 8 composed of the film 7, the film thickness of the Zn film 7 hardly affected the current-voltage characteristics.

From the viewpoint of controlling the film thickness in the vapor deposition forming process, the film thickness of the Zn film 7 in the n-electrode 8 is preferably 10 nm or more. It is more preferably 50 nm or more, and most preferably 150 nm or more.

Next, with respect to the n electrode 8 composed of the AlSi alloy film 6 and the Zn film 7, the Si content in the AlSi alloy film 6 was examined. The result is shown in FIG. In this case, the AlSi alloy film 6 and the Zn film 7 each have a constant film thickness of 15 nm.
The content of Si in the Si alloy film 6 is 1% by weight, respectively.
And 5% by weight, current-voltage characteristics were measured by the same method as in FIG.

In FIG. 9, the graph L shows that the Si contents which were not subjected to any heat treatment after formation were 1% by weight and 5%.
It shows the results for each of the n-electrodes 8% by weight. On the other hand, the graph M shows that after the formation, the heat treatment was performed at 300 ° C. for 5 minutes in a nitrogen atmosphere, and the n contents of Si content were 1 wt% and 5 wt%.
The results of the electrode 8 are shown.

As shown in the graph L of FIG. 9, the Si content in the AlSi alloy film 6 is 1% by weight and 5% by weight.
In any of the above cases, the n-electrode 8 not subjected to heat treatment
In, good ohmic characteristics can be obtained. Further, as shown in the graph M, regardless of whether the Si content in the AlSi alloy film 6 is 1% by weight or 5% by weight, such an n-electrode 8 is heat-treated at 300 ° C. for 5 minutes. However, the ohmic characteristics of the electrode are not deteriorated and good ohmic characteristics can be obtained.

Thus, the AlSi alloy film 6 and the Zn
In the n-electrode 8 composed of the film 7, the Si content in the AlSi alloy film 6 hardly affected the current-voltage characteristics.

The Si of the AlSi alloy film 6 of the n-electrode 8 is
Is preferably 10% by weight or less, more preferably 5% or less, and most preferably 2% or less.

FIG. 10 is a schematic sectional view showing another example of the light emitting diode element according to the present invention.

Light-emitting diode element 101 shown in FIG.
Is the light emitting diode device 10 of FIG. 1 except for the following points.
It has the same structure as 0.

In the light emitting diode element 100 described above, the n-electrode 8 is composed of the AlSi alloy film 6 and the Zn film 7, but the light emitting diode element 101 of this example is the AlSi alloy film 11, the Zn film 12 and the Au film 13. Has an n-electrode 14 which is sequentially laminated.

In this case, for example, the AlSi alloy film 11 of the n-electrode 14 has a film thickness of 20 nm, the Zn film 12 has a film thickness of 100 nm, and the Au film 13 has a film thickness of 300 nm. The Si content in the AlSi alloy film 11 is 1% by weight.

In such a light emitting diode element 101, the p electrode 5 is in ohmic contact with the p-GaN layer 4 and the n electrode 14 is in ohmic contact with the n-GaN layer 2.

In the light emitting diode element 101 having the n-electrode 14 composed of the AlSi alloy film 11, the Zn film 12 and the Au film 13 as described above, the n-electrode is heated even if it is heated in the temperature range up to about 600 ° C. The ohmic characteristics of No. 14 do not deteriorate. Therefore, in the manufacturing process, the assembly process, etc.
Even if heating is performed in a temperature range of 00 ° C. or lower, the ohmic characteristics of the n-electrode 14 do not deteriorate, and the n-GaN layer 2
Stable and highly reliable n-electrode that makes ohmic contact with
4 can be realized.

As described above, in the light emitting diode element 101, the n electrode 14 which is an ohmic electrode having extremely stable characteristics can be easily obtained without alloying by heat treatment.

The light emitting diode element 1 of FIG.
In No. 00, the ohmic characteristics of the n-electrode 8 did not deteriorate even if heating was performed in the temperature range up to about 400 ° C., whereas in the light emitting diode element 101 of this example,
The ohmic characteristics of the n-electrode 14 will not be deteriorated even if heating is performed at a temperature higher than that of the light emitting diode element 100, specifically, in a temperature range up to about 600 ° C. this is,
In the n-electrode 14 of the light emitting diode element 101, Z
This is because the Au film 13 is formed on the n film 12.

For example, in the case of the n-electrode 8 in which the Zn film 7 is simply formed on the AlSi alloy film 6 like the light emitting diode element 100, the melting point of Zn is relatively low at about 400 ° C. When the n-electrode 8 is heated at a high temperature such as 600 ° C., the Zn film 7 begins to melt and evaporate. Therefore, in this case, the melting point is 40
It is difficult to heat at a temperature higher than the temperature around 0 ° C.

On the other hand, in the case of the n-electrode 14 in which the Au film 13 is formed on the Zn film 12 like the light emitting diode element 101, since the Zn is covered with Au, it is higher than the melting point of Zn. The Zn film 12 does not melt and evaporate even if heated at a temperature. Therefore, 6
It becomes possible to perform heating within a temperature range up to about 00 ° C.

Further, in the n-electrode 14 in which the Au film 13 is formed on the Zn film 12 as described above, the Au film 1
Wire bonding can be performed using 3 as a bonding pad, and the adhesion strength with the Au wire can be improved.

Next, the AlSi alloy film 11 as described above,
The current-voltage characteristics of the n-electrode 14 formed by sequentially stacking the Zn film 12 and the Au film 13 were examined when the heat treatment was performed at various temperatures.

When measuring such current-voltage characteristics, as shown in FIG. 11, the AlSi alloy film 11, the Zn film 12, and the Au film 13 were formed on the n-GaN layer 10 by the electron beam evaporation method. One pair of n-electrodes 14 was formed by laminating in order, and the voltage applied between the pair of n-electrodes 14 and the current flowing between the pair of n-electrodes 14 were measured.

Here, the carrier concentration of the n-GaN layer 10 is 4 × 10 ¹⁸ cm ⁻³ , the thickness of the AlSi alloy film 11 is 30 nm, the thickness of the Zn film 12 is 100 nm, and the thickness of the Au film 13 is 10 nm. The film thickness was 300 nm.

FIG. 12 shows the AlSi alloy film 11 and the Zn film 1.
2 is a diagram showing measurement results of current-voltage characteristics of an n-electrode 14 formed by sequentially stacking 2 and an Au film 13. In FIG. 12, graph N shows the result of the n-electrode 14 which was not subjected to any heat treatment after formation, and graph O is the result of the n-electrode 14 which was subjected to heat treatment at 500 ° C. for 5 minutes in a nitrogen atmosphere after formation. The results are shown in the graph P. In the graph P, the n-electrode 1 was heat-treated in a nitrogen atmosphere at 400 ° C. for 5 minutes.
4 shows the result of FIG. 4, Graph Q shows the result of the n electrode 14 which was heat-treated at 300 ° C. for 5 minutes in a nitrogen atmosphere after formation, and Graph R shows the result at 200 ° C. in a nitrogen atmosphere after formation. It shows the result of the n-electrode 14 which was heat-treated for 5 minutes.

As shown in the graph N of FIG. 12, good ohmic characteristics are obtained in the n-electrode 14 which is not heat-treated. Further, as shown in graphs O to R, n
In the electrode 14, even when the heat treatment is performed at 500 ° C., 400 ° C., 300 ° C., and 200 ° C. for 5 minutes, the ohmic characteristics of the electrode do not deteriorate, and good ohmic characteristics are obtained.

As described above, the AlSi alloy film 11, Zn
An n-electrode 14 formed by sequentially laminating a film 12 and an Au film 13.
In the above, it was clarified that it is stable even when the temperature changes and it is possible to prevent the deterioration of the ohmic characteristics due to the heat treatment.

Next, the AlSi alloy film 11 as described above,
A change in contact resistance of the n-electrode 14 formed by sequentially stacking the Zn film 12 and the Au film 13 at various temperatures, and an n-type structure of the conventional structure formed by sequentially stacking the Ti film, the Al film, and the Ti film The change in the contact resistance of the electrode when the electrode was heat-treated at various temperatures was examined, and the results were compared and examined. The result is shown in FIG.

As shown in FIG. 13, the AlSi alloy film 1
1, a Zn film 12 and an Au film 13 are sequentially stacked.
The electrode 14 is not subjected to any heat treatment after formation (non-heat treatment), and is formed in a nitrogen atmosphere at 200 ° C. for 3 ° C. after formation.
In any case where the heat treatment was performed at 00 ° C., 400 ° C. and 500 ° C. for 5 minutes, the contact resistance was smaller than that of the conventional electrode having the Ti film / Al film / Ti film laminated structure, and good ohmic characteristics were obtained. To be

In this case, the conventional electrode having the Ti film / Al film / Ti film laminated structure shows a contact resistance change of two digits or more due to the heat treatment in the temperature range up to 500 ° C. It can be seen that the n electrode 14 formed by sequentially stacking the film 11, the Zn film 12, and the Au film 13 has a small change in contact resistance due to heat treatment and exhibits an extremely stable state.

In the above, the AlSi alloy film 1 is used.
1, the n-electrode 14 formed by sequentially stacking the Zn film 12 and the Au film 13 has been described.
Consider a case in which an n electrode is formed by laminating a metal film other than the Au film on the film.

For example, a Zn film is laminated on an AlSi alloy film, and a Ni film, a Pt film, a Pd film, a Mo film,
The n-electrode can be formed by laminating any one of the Ta film, the W film and the AuZn alloy film. In the following, the case where an AuZn alloy film, a Pt film, a Ni film and a Pd film are formed on the Zn film will be considered.

Here, the film thickness of the AlSi alloy film is 30 n.
In the case where the thicknesses of the m and Zn films are constant at 50 nm and an AuZn alloy film having a thickness of 150 nm is formed on the Zn film, Z
When a Pt film with a film thickness of 200 nm is formed on the n film, Zn
When a Ni film having a thickness of 200 nm is formed on the film and Z
For each of the cases where a Pd film having a film thickness of 200 nm was formed on the n film, the current-voltage characteristics were measured using the same method as that described above with reference to FIG. For comparison, the current-voltage characteristics were also measured in the case where a 200 nm thick Au film was formed on the Zn film. The result is shown in FIG.

In FIG. 14, graph S shows the result of each n-electrode when no heat treatment was performed after formation. On the other hand, the graph T shows the result of each n-electrode when heat-treated at 300 ° C. for 5 minutes in a nitrogen atmosphere after formation.

As shown in the graph S of FIG. 14, in any of the AuZn alloy film, the Pt film, the Ni film and the Pd film formed on the Zn film, the same heat treatment as in the case of forming the Au film was performed. If not performed, good ohmic characteristics can be obtained at the n-electrode. Further, as shown in the graph T, in the case where the AuZn alloy film, the Pt film, the Ni film and the Pd film were formed on the Zn film, the heat treatment was performed at 300 ° C. for 5 minutes as in the case where the Au film was formed. However, the ohmic characteristics of the electrodes do not deteriorate, and good ohmic characteristics can be obtained.

On the Zn film, Ni film, Pt film, Pd
In the n-electrode formed by laminating a film, a Mo film, a Ta film, a W film, or an AuZn alloy film, it is possible to improve the stability against heat treatment as described above, but in consideration of wire bonding. Most preferably, the Au film is laminated on the Zn film. Therefore, in the light emitting diode element, as shown in FIG.
An n electrode 14 formed by stacking the u films 13 is used.

FIG. 15 is a schematic sectional view showing still another example of the light emitting diode element according to the present invention.

The light emitting diode device 102 shown in FIG.
Is the light emitting diode device 10 of FIG. 1 except for the following points.
It has the same structure as 0.

In the light emitting diode element 100 described above, the n-electrode 8 is composed of the AlSi alloy film 6 and the Zn film 7. However, in the light emitting diode element 102 of this example, the AlSi alloy film 21, the Zn film 22 and the Pt film 23. And an n-electrode 25 formed by sequentially stacking the Au film 24.

In this case, for example, the AlSi alloy film 21 of the n-electrode 25 has a film thickness of 10 nm, the Zn film 22 has a film thickness of 100 nm, the Pt film 23 has a film thickness of 100 nm, and the Au film 24 has a film thickness of 100 nm. The thickness is 300 nm. Also, Al
The Si content in the Si alloy film 21 is 1% by weight.

In such a light emitting diode element 102, the p electrode 5 is in ohmic contact with the p-GaN layer 4 and the n electrode 25 is in ohmic contact with the n-GaN layer 2.

In the light emitting diode element 102 having the n electrode 25 composed of the AlSi alloy film 21, the Zn film 22, the Pt film 23 and the Au film 24 as described above,
Even if heating is performed in a temperature range up to about 600 ° C., the n-electrode 2
The ohmic characteristics of No. 5 do not deteriorate. Therefore, even if the light emitting diode element 102 is heated in the temperature range of 600 ° C. or lower in the manufacturing process, the assembly process, or the like, n
The ohmic characteristics of the electrode 25 do not deteriorate, and n-
It is possible to realize a stable and highly reliable n electrode 25 that makes ohmic contact with the GaN layer 2.

As described above, in the light emitting diode element 102, the n electrode 25 which is an ohmic electrode having extremely stable characteristics can be easily obtained without alloying by heat treatment.

The light emitting diode element 1 shown in FIG. 1 is used.
In No. 00, the ohmic characteristics of the n-electrode 8 did not deteriorate even when heated in the temperature range up to about 400 ° C., whereas in the light-emitting diode element 102 of this example,
The ohmic characteristics of the n-electrode 25 do not deteriorate even if the heating is performed at a temperature higher than that of the light emitting diode element 100, specifically, at a temperature range up to about 600 ° C. this is,
In the n electrode 25 of the light emitting diode element 102, Z
This is because the Pt film 23 and the Au film 24 are formed on the n film 22.

For example, in the case of the n electrode 8 in which the Zn film 7 is simply formed on the AlSi alloy film 6 like the light emitting diode element 100, the melting point of Zn is relatively low at about 400 ° C. When the n-electrode 8 is heated at a high temperature such as 600 ° C., the Zn film 7 begins to melt and evaporate. Therefore, in this case, the melting point is 40
It is difficult to heat at a temperature higher than the temperature around 0 ° C.

On the other hand, in the case of the n electrode 25 in which the Pt film 23 and the Au film 24 are formed on the Zn film 22 like the light emitting diode element 102, Zn is Pt and A.
Since it is covered with u, the Zn film 22 does not melt and evaporate even when heated at a temperature higher than the melting point of Zn. Therefore, it becomes possible to perform heating within a temperature range up to about 600 ° C.

Furthermore, in the n-electrode 25 thus formed with the Au film 24, it is possible to perform wire bonding by using the Au film 24 as a bonding pad, and improve the adhesion strength with the Au wire. It becomes possible.

Next, the AlSi alloy film 21 as described above,
With respect to the n electrode 25 formed by sequentially stacking the Zn film 22, the Pt film 23, and the Au film 24, the current-voltage characteristics were examined when the heat treatment was not performed and when the heat treatment was performed at 300 ° C.

When measuring such current-voltage characteristics, as shown in FIG. 16, an AlSi alloy film 21, a Zn film 22, a Pt film 23, and an Au film 24 are sequentially laminated by an electron beam evaporation method. One pair of n-electrodes 25 was formed on the n-GaN layer 10, and the voltage applied between the pair of n-electrodes 25 and the current flowing between the pair of n-electrodes 25 were measured.

The carrier concentration of the n-GaN layer 10 is 4 × 10 ¹⁸ cm ⁻³ , the thickness of the AlSi alloy film 21 is 30 nm, the thickness of the Zn film 22 is 50 nm, and the thickness of the Pt film 23 is 30 nm. The film thickness was 100 nm, and the film thickness of the Au film 24 was 100 nm.

The current-voltage characteristics of the n-electrode 25 formed by sequentially stacking the AlSi alloy film 21, the Zn film 22, the Pt film 23 and the Au film 24 as described above were measured.
Results similar to those shown in 4 are obtained.

That is, when no heat treatment is performed after the formation, good ohmic characteristics are obtained as shown in the graph S of FIG. In addition, as shown in the graph T of FIG. 14, after formation, the temperature is 300 ° C. in a nitrogen atmosphere.
Even when the heat treatment is performed for 5 minutes, the ohmic characteristics of the electrode do not deteriorate in the n-electrode 25, and good ohmic characteristics can be obtained.

In the above, P is formed on the Zn film 22.
Although the n electrode 25 formed by stacking the t film 23 has been described, an n electrode formed by stacking a metal film other than the Pt film on the Zn film may be formed.

For example, a Ni film, a Pd film and a Mo film are formed on the Zn film.
A film, a Ta film, a W film, or an AuZn alloy film may be laminated. Even in this case, it is possible to improve the stability of the n-electrode against heat treatment. Further, in this case, the surface (uppermost layer) of the n-electrode is A
Since it becomes the u film 24, the adhesion strength with the Au wire can be improved by wire bonding.

In addition, in the above, A is formed on the Pt film 23.
Although the n electrode 25 formed by laminating the u film 24 has been described, an n electrode formed by laminating a metal film other than the Au film on the Pt film may be formed.

For example, a Ni film, a Pd film, and a Mo film are formed on the Pt film.
A film, a Ta film, a W film, or an AuZn alloy film may be laminated. Further, an Au film is laminated on the Zn film laminated on the AlSi alloy film, and a P film is further formed on this Au film.
It is also possible to stack t films.

In these cases, it is possible to improve the stability of the electrode under high temperature conditions, but since the surface layer (uppermost layer) of the n electrode is not an Au film,
It is not possible to improve the adhesion strength by wire bonding. Therefore, in consideration of wire bonding, it is most preferable that the surface layer of the n-electrode is an Au film. Therefore, in the light emitting diode element, as shown in FIG.
As shown in, the n electrode 25 having the Au film 24 formed on the surface layer is used.

In the above, the sapphire substrate 1
Light emitting diode element 10 having a semiconductor layer formed thereon
Although 0, 101, and 102 have been described, the n-electrode according to the present invention can be applied to a light emitting diode element using a SiC substrate or the like instead of the sapphire substrate 1.

Further, GaN is used instead of the sapphire substrate 1.
A substrate may be used. For example, the n electrode according to the present invention may be applied to a light emitting diode element in which a semiconductor layer is formed on an n-GaN substrate. In this case, the n-electrode according to the present invention is formed on the surface of the n-GaN substrate opposite to the semiconductor layer crystal growth surface.

The n-electrode according to the present invention is not limited to GaN, but may be AlGaN, InGaN, AlInGaN, BG.
It can be used as an ohmic electrode for other GaN-based semiconductors such as aN, BAlGaN, and BInGaN.

Although the case where the present invention is applied to the light emitting diode element has been described above, the present invention can also be applied to other semiconductor light emitting elements such as a semiconductor laser element. The present invention can also be applied to other semiconductor elements such as field effect transistors and bipolar transistors formed of GaN-based semiconductors.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a light emitting diode element according to the present invention.

FIG. 2 is a schematic process cross-sectional view showing a method for manufacturing the light emitting diode device of FIG.

FIG. 3 is a schematic process sectional view showing a method for manufacturing the light emitting diode device of FIG.

FIG. 4 is a diagram showing a method for measuring current-voltage characteristics of an n-electrode of the light emitting diode device of FIG.

5 is a diagram showing measurement results of current-voltage characteristics of an n-electrode of the light emitting diode element of FIG.

FIG. 6 is a diagram showing measurement results of current-voltage characteristics of an n-electrode composed only of an AlSi alloy film.

7 is an AlSi of n-electrode of the light emitting diode device of FIG.
Current of n-electrode when alloy film thickness is changed-
It is a figure which shows the measurement result of a voltage characteristic.

FIG. 8 is a diagram showing measurement results of current-voltage characteristics of the n-electrode when the thickness of the Zn film of the n-electrode of the light emitting diode element of FIG. 1 was changed.

9 is an AlSi of n-electrode of the light emitting diode device of FIG.
N when the Si content in the alloy film is changed
It is a figure which shows the measurement result of the current-voltage characteristic of an electrode.

FIG. 10 is a schematic cross-sectional view showing another example of the light emitting diode element according to the present invention.

FIG. 11 shows a current flowing through an n-electrode of the light emitting diode element of FIG.
It is a figure which shows the measuring method of a voltage characteristic.

FIG. 12 shows a current flowing through an n-electrode of the light emitting diode element of FIG.
It is a figure which shows the measurement result of a voltage characteristic.

13 is a diagram showing contact resistances of the n-electrode and the n-electrode of the conventional structure of the light emitting diode element of FIG.

14 is a diagram showing measurement results of current-voltage characteristics of an n-electrode when a Pt film, a Ni film, a Pd film and an AuZn film were formed in place of the Au film of the n-electrode of the light emitting diode element of FIG. .

FIG. 15 is a schematic cross-sectional view showing still another example of the light emitting diode element according to the present invention.

16 is a diagram showing a method for measuring a current-voltage characteristic of an n-electrode of the light emitting diode device of FIG.

FIG. 17 is a schematic process cross-sectional view showing a method for manufacturing a conventional light emitting diode element.

18 is a diagram showing a method for measuring the current-voltage characteristic of the n-electrode of the light emitting diode device of FIG.

19 is a diagram showing measurement results of current-voltage characteristics of the n-electrode of the light emitting diode device of FIG.

[Explanation of symbols]

1 sapphire substrate 2,10 n-GaN layer 3 light emitting layer 4 p-GaN layer 5 p electrode 6,11,21 AlSi alloy film 7,12,22 Zn film 8, 14, 25 n electrode 13,24 Au film 23 Pt film 100, 101, 102 Light emitting diode element

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50 H01L 21/28

Claims (8)

(57) [Claims] 1. A semiconductor device comprising an n-type nitride semiconductor and an ohmic electrode formed on the n-type nitride semiconductor, wherein the ohmic electrode contains zinc.
Formed by closely adhering to the above-mentioned metal film of n-type nitride semiconductor
And a second metal film made of aluminum-silicon alloy
And the first metal film is in close contact with the second metal film.
A semiconductor element characterized by being formed by . 2. The ohmic electrode is the first metal.
A third metal film containing gold, which is formed in intimate contact with the film, is further formed.
The semiconductor device according to claim 1, characterized by comprising. 3. The ohmic electrode is formed of the first metal.
Nickel, platinum, palladium,
Molybdenum, gold, tantalum, tungsten or gold / sub
Third metal consisting of one or more metal films containing lead alloy
Film and gold formed in close contact with the third metal film and including gold
A fourth metal film is further provided.
1. The semiconductor device according to 1 . 4. The n-type nitride-based semiconductor is boron,
Low levels of helium, aluminum, indium and thallium
The semiconductor device of claim 1, wherein the containing Nakumoto one. 5. The film thickness of the second metal film is 70 nm or less.
The semiconductor device according to any one of claims 1 to 4, characterized in that. 6. A step of forming an n-type nitride semiconductor, and a step of forming a first metal film containing zinc on the n-type nitride semiconductor.
By forming it, ohmic charge can be applied without heat treatment.
A step of forming a pole, wherein the step of forming the ohmic electrode includes the step of forming the n-type nitride.
The second one consisting of aluminum-silicon alloy on the base semiconductor
A step of forming a metal film in close contact with the second metal film
And a step of forming the first metal film in close contact with each other.
And a method for manufacturing a semiconductor device. 7. The step of forming the ohmic electrode comprises :
Adhering a third metal film containing gold on the first metal film
7. The method according to claim 6, further comprising a forming step.
Method for manufacturing mounted semiconductor device. 8. The step of forming the ohmic electrode comprises :
On the first metal film, nickel, platinum, palladium, molybdenum
Ribden, gold, tantalum, tungsten or gold / zinc
Third metal film consisting of one or more metal films containing an alloy
And forming gold on the third metal film.
And a step of forming a fourth metal film in close contact with each other.
8. A method of manufacturing a semiconductor device according to claim 7, wherein
Law.